With two House committees set to take up the Republican replacement plan for the Affordable Care Act on Wednesday, party leaders have begun trying to sell the proposal to the American public.

Leading the effort is President Trump, who met with Republican House leaders at the White House, saying he is "proud to support the replacement plan released by the House of Representatives."

Earlier, the President tweeted on Tuesday morning that the "wonderful new Healthcare Bill is now out for review and negotiation."

The word negotiation is important. Congressional Democrats are uniformly opposed to the Republican makeover of Obamacare. Democratic Sen. Chris Murphy of Connecticut tweeted the GOP bill is "just a skeletal, slapdash, mean-spirited version of the ACA that would slash insurance coverage, spike costs."

Many Republicans are also expressing doubts, and GOP Congressional leaders can afford few defections.

GOP Sen. Rand Paul called the plan "Obamacare lite." "It will not pass. Conservatives aren't going to take it," Paul told Fox News. He said the bill was a bailout for insurance companies, citing a provision that would force people to pay a 30 percent penalty to insurance companies for going without and then resuming coverage.

At a briefing with reporters on Tuesday, House Ways and Means Committee Chairman Kevin Brady of Texas, one of the bill's authors, responded to the charge, calling the proposal "Obamacare gone."

He said that "as Republicans, we have a choice, we can act now or we can keep fiddling around and squander this opportunity."

The proposal would continue popular parts of the ACA, including stipulations that people with pre-existing conditions should be able to buy coverage and that adult children up to age 26 can be covered on their parents' health plan.

Republicans haven't placed a price tag on their proposal. The Congressional Budget Office hasn't yet "scored" the plan, and won't by the time the House starts work on the measure.

On NBC's Today show, White House Budget Director Mick Mulvaney said it was unfair to compare how many people would be covered under the GOP plan to the ACA, also known as Obamacare.

Mulvaney said Obamacare "made insurance affordable, but care impossible to afford." He said deductibles under the ACA were too high. "So people could say they have coverage, but they couldn't actually get the medical care they needed when they get sick."

He said the plan will bring "tremendous savings" because it will allow states more control over Medicaid costs.

At a White House briefing, Health and Human Services Secretary Tom Price said the Trump administration believes "there will be a decrease in premiums." Asked if Trump supports the House measure, Price said the President does support what Price called "this step in the right direction."

Price repeatedly said this was just the first part of the process.

White House Press Secretary Sean Spicer pointed to two stacks of papers next to his podium, a smaller stack, which he said was the Republican bill and a larger one which he said the the Affordable Care Act.

"Look at the size, this is the Democrat's," Spicer said, pointing to the tall stack. "This is what big government does," he said.

But four Republican senators say they will oppose any plan that doesn't protect people who qualify for coverage under the Medicaid program, which was expanded in some states under the ACA. The four are Rob Portman of Ohio, Shelley Moore Capito of West Virginia, Cory Gardner of Colorado and Lisa Murkowski of Alaska.